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Arthonia epiphyscia Nyl.
Family: Arthoniaceae
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Life habit: lichenicolous, on thallus of Physcia species Thallus: not apparent, with hyaline vegetative hyphae photobiont: absent Ascomata: single or fusing to small groups, developing superficially, without host remnants on the surface, sessile, 0.1-0.24 mm in diam., disc: black, convex, with smooth to rough surface epihymenium: olivaceous brown, 10-15 µm thick, with disintegrating uppermost hyphae hymenium: hyaline, 40-50 µm tall, interascal hyphae 2 µm wide; subhymenium: medium brown, 50-70 µm thick, with cloddy pigments in intercellular spaces asci: clavate, 30-40 x 14-17 µm, 8-spored, lateral walls not thickened ascospores: hyaline, 1-septate, obovate, lower cell attenuated, smooth, 14-16 x 5-7 µm, without an epispore Pycnidia: not seen Chemical reactions: ascomatal gels I+ red, KI+ blue; asci with KI+ blue ring-structure. Substrate and ecology: see host World distribution: subcosmopolitan Sonoran distribution: Arizona (San Francisco Peaks) and eastern Sonora (Sierra Madre Occidental). Note: Arthonia epiphyscia is distinguished from Arthonia phaeophyscia by its superficially developing ascomata.